Milk Composition & Synthesis
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Milk Composition
Physicochemical Properties

At first , milk might seem to be a simple white liquid. But in fact,
it is a complex mixture of a wide range of compounds imprortant to the
neonate. The gross properties of milk include:

Milk is an emulsion of fat globules, and

a suspension of casein micelles (casein, calcium, phosphorous),

all of which are suspended in an aqueous phase,

that contains solublized lactose, whey proteins, and some minerals.

Leukocytes in milk are part of the suspended phase.

In
the diagram below, milk is viewed at two magnifications; the left view
is what would be seen at about 500X magnification, and the right view
at about 50,000X. This illustrates that milk is an emulsion of milk fat
globules (left view) in a partially stable emulsion of the plasma phase
of milk (the skim milk). In the right view, the casein micelles are in
a colloidal suspension in the serum phase of milk (the whey). Milk fat
globules in cow milk range in size from 0.1 to 15 micrometers. Milk fat
has a density of about 0.92 g/ml. Calculations of the total surface area
of fat globules in a liter of milk is about 80 square meters. Casein micelles
range in size from about 10 to 300 nanometers and have a density of 1.11
g/ml. The number of casein molecules in a micelle ranges from 20,000 to
150,000. The calcium content in micelles is about 8 g/ 100 g casein.